Memoirs of a Nun , which began as a joke and grew into a masterpiece, was one of the loudest salvos fired in the continuing battles between the clergy and the intelligentsia which defined so much of eighteenth-century French history.  Diderot's story of a novice held in a convent against her will and forced to undergo curious spiritual and sexual trials displays all the brilliance, icy wit, and worldliness of the Enlightenment at its best.